Advances in electronics, wireless communications, and global positioning devices have led to impressive developments in various tracking and tagging devices. Such devices are available for both personal property (“assets”) and persons.
In the case of asset tagging, the technology options include passive, semi-passive, and active tags, which are placed on an item of property. These tags differ with respect to factors such as power usage and whether they merely reflect an incoming signal or actively transmit a signal. Passive tags are those that are queried by a radiated source, such as a scanner. Active tags are battery-based and radiate their own signals.
Typically, asset tagging systems are portal based, which means that a tag is queried when the asset to which it is attached is moved through a checkpoint, such as a gateway at an industrial site. Thus, asset tagging devices tend to focus on entry or exit of an asset at a particular location, rather than the item's path of movement.
In the case of personnel, it is especially important to be able to track persons as they move about. Tracking devices may be in accord with any one of a number of different technology options. GPS devices rely on GPS satellite visibility. “Local GPS” devices use local towers that generate GPS-like signals. Cellular devices require cell towers in a given range. Mobile beacon devices transmit a signal that is received by multiple receivers that determine location.
For today's existing tagging and tracking systems, there are a number of communications options. Commercial services, such as cellular, PCS, or paging services, may be leased from an appropriate service provider. Alternatively, for a particular user of a tagging or tracking system, a unique communications network can be established for that user, such as a two-way radio, or wired or wireless Ethernet system.